Self-sustained liquid circulating seal system



D. ARONSON Aug. 25, 1964 SELF-SUSTAINED LIQUID CIRCULATING SEAL SYSTEMFiled Jan. 23, 1963 Z2 ssoRBER CONDENS FIG. 2 DAVID ARONSON INVENTOR. /4

United States Patent 3,145,542 SELF-SUSTA; ED LIQUID CERCULATING SEALSYSTEM David Aronson, Upper Montclair, N..i., assignor to WorthingtonCorporation, Harrison, N..i., a corporation of Delaware Filed Jan. 23,1963, Ser. No. 253,363 12 Claims. (Cl. 62-141) The present inventionrelates to a liquid seal arrangemeat. It relates in particular to sealcooling and flushing means in a refrigeration system including a pumpcirculating a refrigerant or absorbent mixture through the system atsubatmospheric conditions.

Refrigeration systems of the type contemplated consist of elementsconnected to circulate a solution made up of an absorbent such as abrine, and a refrigerant such as water. Characteristic of the normalabsorption circuit is the circulation of solution in various degrees ofconcentration. To provide such circulation, generally a liquid pumpingmeans is provided especially when related machine elements are disposedat difierent levels.

Absorption machines often employ two and frequently three or more liquidmoving pumps. Because the major portion of the system is operated atsub-atmospheric pressure it is essential that the entire apparatus besufiiciently air-tight to prohibit inleaked air which would lead togreatly reduced efiiciency. Normally, inleaked air is removed by apurging arrangement. However, where the amount of leaked air becomesexcessive, the purger may be of inadequate capacity to properly removeair and other non-condensibles which have penetrated the system.

The simplicity of the normal absorption unit as contrasted with othertypes of refrigeration systems makes it commercially attractive. Thesemachines are particularly advantageous since they may be runcontinuously, are self-regulatory in capacity adjustment, andconsequently require only a minimum degree of maintenance. Thus,equipment operated in conjunction with the basic absorption unitembodies of necessity a construction requiring little or no maintenancewhile functioning over long periods of time.

It is therefore an object of the present invention to provide aself-sustaining liquid circulatory system for cooling and flushing sealjoints.

It is a further object to provide a self induced liquid circulatingsystem for efiectively removing heat from cooperating seal facesoperating under sub-atmospheric conditions.

It is a still further object to provide a refrigeration system operableunder reduced pressure and normally pumping an absorbent solution, andmeans cooperative with the system for liquid cooling pump seal faceswhich otherwise become heated due to rubbing of the rotating seal faceagainst a stationary face.

These and other objectives of the invention will be come clear to thoseskilled in the art from the following description of the invention madein conjunction with the appended drawings, in which:

FIGURE 1 is a diagrammatic representation of the present seal coolingarrangement incorporated into an absorption refrigeration systemoperating at a pressure less than atmospheric.

FIGURE 2 is an enlarged view in cross-section of a liquid seal of thetype presently contemplated.

In accomplishing the aforementioned objectives, the invention in briefcontemplates a refrigeration system operative at sub-atmosphericpressure and interconnected with a cooling arrangement for cooperatingpump seal faces. Such seals pass a liquid between slidably engaged3,145,542 Patented Aug. 25, 1964 faces to function as a lubricant and asa fluid-tight barrier about a pump shaft.

The instant cooling arrangement includes a reservoir or tank having atleast a pair of interconnected chain bers holding a supply of sealantliquid to be circulated. Separating means disposed between therespective chambers acts to maintain a substanitally equal level ofliquid in both chambers and permits unidirectional flow of the sealantmedium from hot side to cold side of the reservoir.

One of the chambers is connected by a first line to the seal faces to bechilled and carries a column of liquid which is cooled by means of aliquid circulating cooling coil normally submerged in the sealantliquid.

The cooled liquid flows under a gravity head to the seal assembly tolubricate and cool the seal faces. Liquid then passes to a heatexchanger which may use the ambient air as heat source, and which warmsthe sealant liquid causing the latter to rise in the upgoing pipe orline and enter the hot side of the reservoir.

Natural circulation of sealant liquid under normal operating conditionsis maintained by virtue of a temperature differential existing betweenthe respective inlet and outlet lines to the reservoir. This temperaturedifference effectuates a sufficient pressure dilferential in coolantcarrying columns to induce an adequate flow for lubricating and coolingseal faces without an appreciable rise in the temperature of the sealantliquid in its passage across the seal faces.

A further requirement of the intant system is that it affords amplewarning of incipient failure at either of two seal face assemblies.Following normal seal construction, and as illustrated in FIGURE 2, oneseal face assembly prevents sealant liquid from leaking to the ambient,while the other assembly prevents the sealant liquid from leaking intothe pump. Should either seal begin to deteriorate and increase itsminiscule leak flow rate, liquid in the reservoir will be depleted andby means of a suitable alarm system associated with the liquid level,will alert operating personnel to the possible danger.

Concurrently, it is necessary to assure that the extremely small thoughcontinuous leakage does not lead to a drop in liquid level which couldcause a false alarm. A degree of liquid makeup is provided by extractingmoisture from the atmosphere condensing liquid on the cooling coil andso raising the liquid level. As liquid level in the reservoir builds up,the cooling coil is gradu ally immersed and in so doing restricts therate of condensation from the atmosphere and thus is self-regu lating,avoiding any overflow.

Normally when water chilling is required for air con ditioningapplications the humidity is sufiiciently high to cause the condensationdescribed above. There may of course be instances where this conditiondoes not exist and in such arid locations, any of the several types ofwell known humidifiers may be placed in communication with the air spaceabove the cooling coil to supply relatively high humidity air. Becauseof extremely low water makeup rates, no forced circulation is required,but diffusion or natural convection is sufiicient to convey the watervapor to the cooling coils on which it condenses.

Where the signalling or alarm feature of this invention is deemed to beunnecessary, makeup water may be supplied by a simple form of liquidlevel controller.

While the novel features of the invention are not entirely contingent ona particular disposition of absorber elements, the instant-arrangementillustrates an embodiment in which the invention has been operativelyassimilated to great advantage.

Referring to FIGURE 1, the absorption unit consists of basic elementsincluding an absorber 11, a generator 12 having a coil 12' connected toa source of heating fluid, a condenser 13, an evaporator 14 and a heatexchanger 15. These elements are connected by piping and associatedcontrol means to define a closed refrigeration system. The circulatedsolution in the system as previously mentioned may consist ofrefrigerant and absorbent material such as water and lithium bromide.Circulation of the solution in varying concentrations is motivatedeither by gravity flow or by the pumping means hereinafter described ingreater detail.

Absorber 11 and evaporator 14 are disposed within a first low pressureshell enclosure 17 whereby heated water vapors may rise into theabsorber and be contacted by sprayed streams of concentrated brinesolution. Condenser 13 and generator 12 are positioned in a highpressure second shell enclosure 17' and relatively disposed with respectto each other to pass vaporized refrigerant to the condenser. In thegenerator 12, refrigerant vapors are boiled from weak brine solution forthe purpose of concentrating the latter. Vapor thus driven from thebrine solution being concentrated is condensed in the indirectly cooledcondenser located in the higher pressure shell. Condensate is thenpassed upward through conduit 25 from the high pressure shell to the lowpressure portion of the system.

Liquid formed in condenser pan 18 is directed through conduit 25 to thelow pressure side of the system into which it flashes for coolingchiller coils 14' by evaporation. The quantity of refrigerant circulatedover water carrying heat transfer tubes in the chiller, and the quantityof brine circulated over tubes in the absorber are normally in excess ofthat required for proper functioning of the respective units.

Liquid in the system is circulated from the uppermost positionedabsorber to the lowermost positioned generator and vice versa. In thepresent arrangement, conduit means 16 is provided for gravity feeding astream of weak solution from absorber 11 through the tube side of heatexchanger and to the generator 12 for concentrating the solution. Afterbeing concentrated by removal of water vapor, strong solution flows fromthe generator through line 15', passes through heat exchanger 15 shell,and thence to the suction of ejector 18. The ejector as shown isinterconnected with a pump 19 normally disposed at the lower part of themachine receiving a gravity flow of solution at its suction 20 andredirecting the same under pressure to spray nozzles 21 located at theupper part of absorber 11 for spraying streams of concentrated solutiononto the absorber tubes 22.

Pump 19, carrying concentrated brine, is normally provided with a liquidseal 23 as shown in FIGURE 2 to prevent inleak of air to the fluidsystem by way of the rotating pump shaft. Because the closedrefrigeration system normally operates continuously for long periods oftime, the pump seal and other similar seals are constructed and arrangedwith cooperating faces to circulate sealant medium to absorb heat fromthe seal, and to maintain a substantially low constant pressure betweenseal components.

Seal 23 as shown in FIGURE 2 is carried on the pump about the pumpshaft, is exemplified by a commercially available type in whichadjacently disposed rotating and non-rotating members 23 and 23b definea sealing face therebetween consisting of a thin liquid layer formedalong the interface of said members.

T he seal cooling arrangement illustrated consists in general of areservoir or tank 26 defining a fluid enclosure and having a panel 27dividing the enclosure into adjacently positioned storage and coolingchambers 28 and 29 respectively. These chambers are interconnectedpermitting unidirectional flow of liquid from 23 to 29.

Weir 27 is intended to operate partially submerged so that the warmliquid entering at 32 can rise and flow over the weir. Cooled liquidleaving contact with the cooling coil 31, sinks because of its higherdensity, and cannot flow backwards across the weir 27, but can onlyleave through opening 36 thus assuring continuous and unidirectionalflow.

Reservoir 26 is vented to the atmosphere so that the cooling circuit isin efiect an open system, and as will be hereinafter described thisfeature permits automatic replenishment of cooling water form theatmosphere when the supply of coolant is reduced.

Tank 26 is preferably positioned at an elevation above the elevation ofpump seal 23. As a matter of convenience, the tank may be disposedadjacent to or in heat exchange contact with evaporator 14 of theabsorption system when water chilled by the system is circulated throughthe tank cooling coil 31.

Storage chamber 2% is provided with at least one inlet 32 and conduitmeans 34 communicated with the outlet 33 of liquid seal 23. Conduit 34extending between said openings may be rigid piping or of flexibletubing as best suited to the apparatus.

Also cooperative with storage chamber 28 there may be a liquid levelcontrol means maintaining a predetermined amount of liquid within thesystem. The control means may consist of any of several commercialarrangements such as the present device which includes a float assemblyactuated by the level of liquid contained in storage chamber 28 betweenpredetermined upper and lower limits. At the lower extremity when thesupply of water is below a predetermined minimum level, the controlmeans will actuate a secondary supply mechanism or source such as watercontained in a secondary tank 30 which is communicated to the storagechamber 28 through conduit 35 including valve 40. Valve 41 is operablyresponsive to liquid level control means to open and introduce a flow ofliquid to the storage chamber 28 when the control means indicates a lowlevel.

Chilled or unchilled water is supplied to secondary tank 30 through aconduit 45 and valve 48 connected to the upstream side of chiller coil14.

While the liquid level control means is described in terms ofintroduction of liquid from the supplementary source, it is not intendedthat this embodiment should constitute a limitation to the invention.For example, a suitable water control means might consist ofcommercially available electrically operated elements connected to asource of water such as city water or refrigerant circulated in theabsorber unit when said refrigerant is also circulated in the seal 23cooling circuit.

Secondary or cooling chamber 29 in tank 26 is provided with at least oneoutlet 36 connected to line 37, which carries cooled liquid to inlet 33of seal 23. Chamber 29 is also provided with coil 31 positioned in suchmanner as to be at least partially immersed in liquid sealant held inchamber 29 prior to introduction of the sealant to inlet 33 of seal 23.

Coil 31 circulates cooling medium which may be loop process water, or isinterconnected into a separate refrigeration system. In the presentarrangement it is convenient to connect the upstream side of coolingcoil 31 through line 46 and valve 47 with the upstream leg of chillercoil 14. Thus a small amount of loop water to be processed by theabsorption refrigeration system will be used for seal cooling.Interconnection of the evaporator and the seal cooling circuit includesvalve 43 and line 44 connecting the outlet leg of coil 31 to thedownstream leg of chil er coil 14.

Tank 26 is provided with a vent 51 or similar means permittingcommunication of the tank interior with the atmosphere. This not onlymaintains the system in an open condition but also permits replenishingthe supply of sealant liquid contained in the system which may becomedecreased or depleted due to evaporation. Thus, coil 31 is so disposedin chamber 39, preferably in a vertical position, to cool a pool ofliquid sealant contained in the cooling chamber at all times. When thepool level drops sufliciently to uncover the upper turns of coil 31,depending on the prevalent atmospheric conditions, an amount of waterfrom the air will be condensed on the coil exposed surface and bedeposited in the cooling chamber. This replenishment of the water supplyis continuous and at a rate depending on ambient conditions and on thetemperature of water circulated through coil 31. When of course thelevel of water in the cooling chamber becomes excessive, coil 31 will becompletely immersed and automatically discontinue further condensation.

Thus, the described system may be largely self-regulating in that boththe minimum level of water in the system and the maximum level arecontrolled and automatically maintained.

Operation of the seal cooling system or loop will be described inconjunction with the absorption arrangement shown in FIGURE 1. Thesystem is provided with a supply of Water which is initially charged toa predetermined level in tank 26, both input line 34 and output line 37being connected to the reservoir to fill said lines. To avoid bubbleformation within the seal circuit, and to preclude the possibility ofairlock, the system may be charged in a manner familiar to commercialpractice as by filling through one leg of the closed loop formed by bothlegs and the seal until water overflows from the other leg.

Thus, with the system fully charged and no temperature differentialexisting between the respective water columns there will be noappreciable movement of Water through the system. As the absorber unitcommences to operate, concentrated solution carried from the system heatexchanger 15 and into pump 19 through ejector 18 will be in a heatedcondition. Much of the heat generated at pump seal faces will betransferred to the seal 23 cooling jacket and to the sealant watercirculated therein. As the absorber continues to operate, the sealcooling system liquid will gradually become heated by direct contactwith the seal engaging faces.

The hot and cold sides of the cooling system defined by panel 27 in thereservoir and seal 23 respectively, will be at slightly differenttemperatures depending on the amount of heat transferred to the watersealant from seal heated faces. Chilled water in the colder leg 37 ofthe loop, having a slightly greater density than water in the heatedreturn leg 34, will in eflect be under a slightly greater head thanwater in the latter line. Theoretically this differential will prompt asuiiicient amount of circulation to provide a continuous passage throughseal passages for both cooling and flushing.

To induce circulation through seal 23 at a greater rate than would becaused by the normal seal temperature differential, the return leg ofthe sealant circulating loop may be subjected to additional heating froman external source. One means to accomplish heat addition in the returnleg 34 or hot side is to position return leg 34 in heat exchange contactwith an external heating element utilizing electricity, steam or othersource. Alternately, leg 34 may be positioned in heat exchange contactwith normally heated 7 elements of the absorber unit such as the outersurface of generator 12 or heat exchanger 14.

Also, in accordance with the invention, it is understood that chillingfluid passed through coil 31 may be supplied rom a source other thanthat presently shown. For example, this portion of the seal circuit mayreceive a flow of cooling fluid from a source external to the absorptionunit such as a sink or may be interconnected with another portion of theabsorber unit itself.

Where, as shown in the drawings, the absorber unit includes a pluralityof pumps moving both hot and cooled solution, the respective pump sealsmay be interconnected in series or parallel. Since the chiller pump 42will ordinarily move cooled liquid, when a series connection is used thechiller pump seal will be connected upstream of absorber pump seal 23.

It is also practical to connect the respective seals in parallel wherebyeach seal receives coolant liquid at approximately the same temperature.Since both arrangements function to provide the sealing and coolingdesired, the particular connection employed is optional.

From the foregoing description it may be appreciated that the inventionconstitutes features which are highly desirable and advantageous to anabsorption or similar refrigeration type apparatus. For example, byeliminating the need for a pump in the seal cooling arrangement, notonly is there a saving in the initial installation but also subsequentmaintenance to the apparatus is reduced. Further, by interconnectingcooling coil 31 with evaporator coil 14', cooling of pump seal 23 isaccomplished by drawing off only so much of the cooled water from theevaporator as is actually required.

While I have confined the foregoing description to an absorption unit ofa particular design for the purpose of illustrating the invention, it isnot intended to so limit the scope of the cooling arrangement. Forexample, the relative disposition of a main absorber apparatus with theseal cooling circuit carries certain limitations which are included in apreferred embodiment of the invention, which limitations may be modifiedand changed without departing from the spirit and scope of theinvention.

What is claimed is:

1. In a closed refrigeration system circulating absorbent solutionincorporating a refrigerant in liquid and vapor phase at pressure belowatmospheric and comprising; an evaporator having a coil includingupstream and downstream sides and carrying chilled liquid, a generator,a condenser and an absorber, a motor driven pump pumping at least aportion of the absorbent solution in liquid phase, said motor drivenpump including a liquid seal associated therewith preventing leakage ofair to the closed system, a liquid seal cooling circuit comprising:

(a) a reservoir forming separate chambers for storage and cooling of aliquid sealant,

(b) said respective storage and cooling chambers being communicated topass liquid therebetween and being positioned substantially equidistantabove the pump liquid seal,

(0) a coil carried in the cooling chamber having inlet and outletopenings andcirculating a chilled medium,

(d) a sealant liquid carrying loop having conduit legs communicating thepump liquid seal with the respective storage and cooling chambers,

(e) liquid sealant flowing in one of the conduit legs in communicationwith the cooling chamber being normally at a lower temperature thanliquid sealant flowing in the other of said legs,

(f) whereby chilled sealant flowing in said one leg having a greaterdensity than warmer coolant in the other leg will induce continuousliquid circulation in the liquid carrying loop.

2. In a closed absorption refrigeration system substantially as definedin claim 1 wherein the coil positioned in the cooling chamber iscommunicably connected with means circulating chilled liquid through theabsorber.

3. In a closed absorption refrigeration system substantially as definedin claim 1 wherein the coil positioned in the cooling chamber is incommunication with the coil in the evaporator carrying chilled liquid.

4. In an absorption refrigeration system substantially as defined inclaim 3 wherein the coil positioned in the reservoir cooling chamberincludes an inlet communicated to the upstream side of the coil in saidevaporator and receiving liquid therefrom, the cooling chamber coiloutlet being in communication with the downstream side of the coil insaid evaporator.

5. In an absorption refrigeration system substantially as defined inclaim 3 including flow control means cooperative with said reservoir andresponsive to the level of liquid therein for controlling the amount ofliquid held in the reservoir storage and cooling chambers within apredetermined limits and containing means associated with the flowcontrol means holding a supply of sealant for addition to the reservoirchambers.

6. In an absorption apparatus substantially as defined in claim 3wherein the leg in said loop carrying warmed liquid sealant is disposedin heat exchange relation with a heat source and receiving heat from thelatter to induce circulation of sealant liquid in the loop regardless oftemperature difierential of liquid between the seal inlet and outlet.

7. In an absorption apparatus substantially as defined in claim 6wherein the said loop leg carrying warm liquid sealant is disposed inheat exchange contact with a surface of the absorption apparatusnormally having a temperature above the temperature of liquid in theother leg of the loop.

8. In combination with an absorption apparatus circulating an absorbentsolution, a liquid carrying pump for said solution having a liquid sealincluding a liquid sealant conducting passage disposed in heat exchangerelationship with normally heated seal engaging faces, said sealantconducting passage having inlet and outlet passing liquid sealanttherethrough, of asystem cooperative with said apparatus circulatingliquid sealant through said passage including:

(a) a reservoir positioned above said seal defining a plurality ofcommunicated chambers holding a supply of liquid sealant,

(b) a cooling element disposed in at least one of said communicatedreservoir chambers and positioned in contact with liquid containedtherein to maintain the liquid in said one chamber at a temperaturelower than liquid held in the other of said plurality of communicatedchambers,

() first conduit means communicating said one chamber containing liquidat a lower temperature with the sealant conducting passage inlet, todirect a stream of chilled coolant to seal engaging faces,

(d) second conduit means communicating the outlet of said sealantconducting passage with the other of the plurality of chambers, saidsecond conduit means carrying heated liquid from the seal engagingfaces, to induce circulation of liquid through said system when sealantflowing in said first and second conduit means is at a temperaturedifferential.

9. In the combination substantially as defined in claim 8 wherein saidrespective plurality of chambers in the reservoir are adjacentlydisposed one to the other to hold sealant liquid at substantially thesame elevation above the seal.

10. In an apparatus substantially as defined in claim 8 including meanscommunicating the reservoir with a source of sealant liquid forintroducing a flow of said liquid to the cooling system to maintain apredetermined quantity of sealant in the system.

11. In a system substantially as defined in claim 8 including flowcontrol means disposed in at least one of said plurality of chambers andcommunicated to a source of liquid for addition of said liquid to thereservoir, said flow control means being operable to introduce saidliquid to the system at a predetermined minimum level.

12. In an absorption system substantially as defined in claim 8including flow control means disposed in at least one of said pluralityof chambers; an auxiliary tank holding a supply of liquid sealant foraddition to the reservoir and in communication therewith, valve meanscommunicating with the auxiliary tank controlling the flow of saidliquid sealant to the system, said valve means being responsive to theflow control means to introduce liquid to the system in response to theliquid level in at least one of said reservoir chambers.

References Cited in the tile of this patent UNITED STATES PATENTS2,133,879 Thearle Y Oct. 18, 1938 2,156,426 Brown et al. May 2, 19392,271,574 Tucker Feb. 3, 1942 2,317,520 Coons Apr. 27, 1943 2,332,150Huff Oct. 19, 1943 2,473,389 Reid June 14, 1949 2,648,957 BerestnefiAug. 18, 1953 2,70l,684 Hirsch Feb. 8, 1955 2,921,445 Ashley Jan. 19,1960 FOREIGN PATENTS 641,565 Canada May 22, 1962

1. IN A CLOSED REFRIGERATION SYSTEM CIRCULATING ABSORBENT SOLUTIONINCORPORATING A REFRIGERANT IN LIQUID AND VAPOR PHASE AT PRESSURE BELOWATMOSPHERIC AND COMPRISING; AN EVAPORATOR HAVING A COIL INCLUDINGUPSTREAM AND DOWNSTREAM SIDES AND CARRYING CHILLED LIQUID, A GENERATOR,A CONDENSER AND AN ABSORBER, A MOTOR DRIVEN PUMP PUMPING AT LEAST APORTION OF THE ABSORBENT SOLUTION IN LIQUID PHASE, SAID MOTOR DRIVINGPUMP INCLUDING A LIQUID SEAL ASSOCIATED THEREWITH PREVENTING LEAKAGE OFAIR TO THE CLOSED SYSTEM, A LIQUID SEAL COOLING CIRCUIT COMPRISING: (A)A RESERVOIR FORMING SEPARATE CHAMBERS FOR STORAGE AND COOLING OF ALIQUID SEALANT, (B) SAID RESPECTIVE STORAGE AND COOLING CHAMBERS BEINGCOMMUNICATED TO PASS LIQUID THEREBETWEEN AND BEING POSITIONEDSUBSTANTIALLY EQUIDISTANT ABOVE THE PUMP LIQUID SEAL, (C) A COIL CARRIEDIN THE COOLING CHAMBER HAVING INLET AND OUTLET OPENINGS AND CIRCULATINGA CHILLED MEDIUM, (D) A SEALANT LIQUID CARRYING LOOP HAVING CONDUIT LEGSCOMMUNICATING THE PUMP LIQUID SEAL WITH THE RESPECTIVE STORAGE ANDCOOLING CHAMBERS, (E) LIQUID SEALANT FLOWING IN ONE OF THE CONDUIT LEGSIN COMMUNICATION WITH THE COOLING CHAMBER BEING NORMALLY AT A LOWERTEMPERATURE THAN LIQUID SEALANT FLOWING IN THE OTHER OF SAID LEGS (F)WHEREBY CHILLED SEALANT FLOWING IN SAID ONE LEG HAVING A GREATER DENSITYTHAN WARMER COOLANT IN THE OTHER LEG WILL INDUCE CONTINUOUS LIQUIDCIRCULATION IN THE LIQUID CARRING LOOP.